System.Security.SecurityException: Request for the permission of type 'System.Web.AspNetHostingPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.

Server Error in '/' Application.

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Security Exception

Description: The application attempted to perform an operation not allowed by the security policy.  To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file.

Exception Details: System.Security.SecurityException: Request for the permission of type 'System.Web.AspNetHostingPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[SecurityException: Request for the permission of type 'System.Web.AspNetHostingPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.] System.Reflection.Assembly._GetType(String name, Boolean throwOnError, Boolean ignoreCase) +0 System.Web.UI.NamespaceTagNameToTypeMapper.GetControlType(String tagName, IDictionary attribs, Boolean throwOnError) +209 System.Web.UI.TagPrefixTagNameToTypeMapper.System.Web.UI.ITagNameToTypeMapper.GetControlType(String tagName, IDictionary attribs) +210 System.Web.UI.MainTagNameToTypeMapper.GetControlType2(String tagName, IDictionary attribs, Boolean fAllowHtmlTags) +242 System.Web.UI.MainTagNameToTypeMapper.GetControlType(String tagName, IDictionary attribs, Boolean fAllowHtmlTags) +17 System.Web.UI.RootBuilder.GetChildControlType(String tagName, IDictionary attribs) +22 System.Web.UI.ControlBuilder.CreateChildBuilder(String filter, String tagName, IDictionary attribs, TemplateParser parser, ControlBuilder parentBuilder, String id, Int32 line, VirtualPath virtualPath, Type& childType, Boolean defaultProperty) +119 System.Web.UI.TemplateParser.ProcessBeginTag(Match match, String inputText) +605 System.Web.UI.TemplateParser.ParseStringInternal(String text, Encoding fileEncoding) +1334

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Version Information: Microsoft .NET Framework Version:2.0.50727.4963; ASP.NET Version:2.0.50727.4971 


Solution:
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If your accessing virtual path from network please change the Identity to "Network Service:


The easy way out is just to go back to using Network Service as an application pool identity instead of the ApplicationPoolIdentity used by IIS 7.5. However, this undermines the new security enforcements that the IIS team has created, and kind of defeats the purpose of using IIS 7.5 as opposed to IIS 7.


If  your hosting an web application within local IIS and virtual path referenced to your local system then use "Local System" as Identity 


It will be work fine..........